T cell therapies have demonstrated efficacy and the therapeutic potential for treating cancers. However, their uses are limited by the presence of an immunosuppressive microenvironment. The immunosuppressive microenvironment includes immune tolerance induced by the interaction between programmed death-1 (PD-1) and PD-L1 ligand (PD-L1). PD-1 is a negative coregulatory receptor on T cells and antigen-presenting cells. The PD-L1 is expressed by several cell types (e.g., tumor cells and other tissue cells), and appears to be dynamically regulated by the immune microenvironment. Therefore, there is a need to address immune tolerance induced by the PD-L1 as to improve the efficacy of T cell therapies.